retreat vs retrograde

retreat is a noun but retrograde is not a noun.

Word	Noun	Adjective	Verb	Adverb
retreat	Yes	No	Yes	No
retrograde	No	Yes	Yes	No

As verbs, retrograde is a hyponym of retreat; that is, retrograde is a word with a more specific, narrower meaning than retreat:

Other hyponyms of retreat include fall back, retreat, back down, back off, back up.

As verbs, retreat and retrograde are synonyms defined as:

retreat (noun)	retrograde (noun)
(military) withdrawal of troops to a more favorable position to escape the enemy's superior forces or after a defeat
withdrawal for prayer and study and meditation
the act of withdrawing or going backward (especially to escape something hazardous or unpleasant)
an area where you can be alone
(military) a bugle call signaling the lowering of the flag at sunset
(military) a signal to begin a withdrawal from a dangerous position
a place of privacy; a place affording peace and quiet

retreat (adjective)	retrograde (adjective)
	of amnesia; affecting time immediately preceding trauma
	moving from east to west on the celestial sphere; or--for planets--around the sun in a direction opposite to that of the Earth
	going from better to worse
	moving or directed or tending in a backward direction or contrary to a previous direction

retreat (verb)	retrograde (verb)
make a retreat from an earlier commitment or activity	get worse or fall back to a previous condition
pull back or move away or backward	go back over
move back	move back
move away, as for privacy	move in a direction contrary to the usual one
	move backward in an orbit, of celestial bodies